Device for the removal of soot dust of fuel oil combustion

ABSTRACT

A device designed for the removal of soot dust of fuel oil combustion. The device is based on the two-stage wet-electrostatic dust removal-desulfurization device, with different numbers of layers of the mesh screen being installed in the wet type dust removal-desulfurization device. This device not only has a relatively high efficiency in both of common dust removal and desulfurization, but also can remove the black smoke from fuel oil combustion efficiently with a removal efficiency ≧99%, and thus solves the present technical problem in the treatment of in the treatment of soot dust of fuel oil combustion. At the same time, with the advantages of cheaper construction cost and economy, the device of the present invention overcomes the disadvantages of the traditional bag filter process, which is expensive and cannot operate desulfurization simultaneously.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a kind of air pollution treatmentdevice, and more particularly to an integrative device with two-stagewet-electrostatic process for dust removal-desulfurization, and forremoval of soot dust of fuel oil combustion.

2. Description of the Prior Art

With the use of fuel oil instead of coal, the air pollution ofindustrial and domestic soot dust (black smoke) of fuel oil combustionhas become more and more serious. However, since the soot dust (blacksmoke) of fuel oil combustion is mainly made of soot due to uncompletedcombustion, and black carbon and a small amount of impurities formedduring combustion process. The soot dust (black smoke) of fuel oilcombustion has the characteristics of high temperature (usually 200-300°C.), oiliness, superfine particle (usually <1 μm), small specificresistance (≦10³ ohm*centimeter (Ω·cm)) and small density. The soot dustis of poor hydrophilic (hydrophobic nature) and is contained ofcorrosive gases (such as SO₂ and HF). The treatment of the soot dust(black smoke) of fuel oil combustion has always been a technical problemin the field of environmental protection. The existing removal techniqueof soot dust (black smoke) of fuel oil combustion mainly includes ESP,wet process for dust removal-desulfurization, bag filter and two-stagewet process-electrostatic dust removal-desulfurization. Due to the lowspecific resistance of the dust (≦10³ ohm*centimeter), which is beyondthe scope of that of the ESP process (10⁴-5*10¹⁰ ohm*centimeter (Ω·cm)),the phenomenon of the black smoke return flow is serious, therefore thetechnique of ESP has poor efficiency in black smoke removal. As the sootdust has the characteristic of superfine particles and hydrophobicnature, with the wet process for dust removal-desulfurization, the blacksmoke cannot be removed efficiently too. Though bag filter has a highremoval efficiency of black smoke, with the characteristics of hightemperature, oiliness and corrosiveness of soot dust, the request formaterial selection of bag is especially high, and cooling measure isrequired, all which will result in high construction cost and impossiblefor simultaneous desulfurization. Therefore, bag filter is rarely used.The newest used two-stage wet type-electrostatic dustremoval-desulfurization device, disclosed in CN Pat. No. 03225616.7, hasa high efficiency in both dust removal and desulfurization, but due tothe soot dust characteristics of low specific resistance, superfineparticles and hydrophobic nature, the removal of black smoke isinefficient and cannot reached the requirement of environmentalprotection.

The present invention has arisen to mitigate and/or obviate theafore-described disadvantages.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a devicefor removing soot dust of fuel oil combustion, which not only has arelatively high efficiency in both of common dust removal anddesulfurization, but also can remove the black smoke of fuel oilcombustion efficiently.

The present invention is based on an integrative device with two-stagewet-electrostatic process for dust removal-desulfurization, disclosed inCN Pat. No. 03225616.7, with different numbers of layers of mesh screeninternally installed in the wet dust removal-desulfurization device. Themesh screen is tangential arranged to the smoke flow. When entering thewet type dust removal-desulfurization device, under the function of thewater gravity and the fan gravitation, the smoke must force through thetiny holes of the mesh screen. While the soot dust (black smoke) andwater force through the mesh screen together, the soot dust (blacksmoke) is surrounded and extruded by water, and the multi-layers of meshscreen make the surrounded and extruded repetitiously, along withintensively collision. Thereby, on the one hand, the soot and blackcarbon are forcibly contacted with water sufficiency until the soot andblack carbon are being totally or partly hydrophilic by water, or partlysurrounded by water. On the other hand, the self-extruded andself-collided of soot and black carbon will form bigger and thickerparticles. When the soot dust and water are forced to be compatiblewhile passes through the holes of the mesh screen, the temperature-heatenergy of the smoke plays an active catalytic effect. Before enteringthe spraying tower, the temperature of smoke is high (200-300° C.). Whenentering the spraying tower, the smoke contacted with water adequately,and the heat of the smoke being absorbed. This cause the smoke'stemperature to dropped to ≦100° C., and help water to obtain a certaintemperature. With the obtained temperature, water can ensure theactivation of the water molecules and play an active catalytic effect inthe hydrophilic of the soot and black carbon. When the soot and blackcarbon are hydrophilic, due to the high specific resistance and gravityof the water, the water serves as a friction intensifier, a weightingagent and an adhesive, which overcome the drawbacks of the hydrophobicnature, low specific resistance, superfine particles and small density,so as to enable the specific resistance of the soot and black carbon toreach the specific resistance scope (10⁴-5*10¹⁰ ohm*centimeter (Ω·cm))of ESP. Thereby, when the hydrophilic soot and black carbon enteredESP-desulfurization device via a smoke duct, it can be easily separatedfrom the smoke by the electrostatic coulomb power and will not bereturned. Then, by passing through an automatic cleaning device, theblack smoke is washed away to a tank, thus reaching the purpose ofremoving the black smoke efficiently.

Through replication experiments of the present invention, results showthat: the removal efficiency of black smoke from fuel oil combustion isrelated to the number and layers of the mesh screen installed inside thewet process device for dust removal-desulfurization. The more number andlayers of the mesh screen, the more chances that the soot and blackcarbon being surrounded, extruded and collided with water, therefore abetter hydrophilic and a higher efficiency of dust removal will be.However, at the same time, the fan's wind pressure loss goes larger, andenergy consumption goes higher. The screen mesh and layers of the meshscreen, which installed in the wet process dust removal-desulfurizationdevice, has the removal efficiency of soot dust (black smoke) range from4-1000 meshes and 1-500 layers respectively, and optimally range from18-30 meshes and 18-30 layers respectively. The tangent angle of theinternal installed mesh screen with the flow direction of the soot dustranges from 10°-90°, and optimally ranges from 60°-90°. In addition, inorder to reduce the wind pressure loss of the fan, the flow direction ofthe smoke is usually the same as that of the spraying water, which isusually from top to bottom. With such an arrangement, part of thewater's potential energy loss can be translate into wind energy, so asto reduce the wind pressure, thus reaching the purpose of energy saving.

The present invention has the following notable effects: The inventionnot only has a relatively high efficiency of common dust removal anddesulfurization, but also can remove the black smoke from fuel oilcombustion efficiently with a removal efficiency ≧99%, and thus solvesthe present technical problem in the treatment of soot dust of fuel oilcombustion. At the same time, with the advantages of cheaperconstruction cost and economy, the device of the present inventionovercomes the disadvantages of the traditional bag filter process, whichis expensive and cannot operate desulfurization simultaneously.

The present invention will become more obvious from the followingdescription when taken in connection with the accompanying drawings,which show, for purpose of illustrations only, the preferred embodimentsin accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the constructional drawing of a dust removal device for sootdust of fuel oil combustion, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, dust removal device for soot dust of fuel oilcombustion, in accordance with the present invention comprises awet-type dust removal-desulfurization device 3, an ESP-desulfurizationdevice 16 and a tank 10. The tank 10 is divided into clear water tankand waste water tank by a partition board 7 located at the center of thetank 10, the lower part of the partition board 7 is installed with afilter screen 9, which enabling the waste water being filtered beforeflowing into the clear water tank. On one side of the tank 10, a manualdust-removing mouth 12 is designed under the water interface 6, while awastewater discharge outlet 11 is set at the lower part of the tank 10.On the other side of the tank 10, an agent-filling opening 5 is designedabove the water interface 6. The wet type dust removal-desulfurizationdevice 3 and the ESP-desulfurization device 16 are connected to theupper part of the tank 10 and are separated by a partition board 19.Thus the wet type dust removal-desulfurization device 3, theESP-desulfurization device 16 and the water interface 6 formed a closedbody. A smoke duct 13 is located above the water interface 6 of the tank10. Different numbers of layers of mesh screen 4 is installed in the wettype dust removal-desulfurization device 3, and the mesh screen 4 istangent to the direction of smoke flow at 10°-90°. A wind inlet 1 isdesigned in the upper part of the wet type dust removal-desulfurizationdevice 3, and a water-spray device 2 is installed on the top of the wettype dust removal-desulfurization device 3, so that the flow directionof the smoke is the same as that of the spraying water from top tobottom. A soot dust guiding board 14 is mounted on the lower part of theESP-desulfurization device 16 that enables the smoke dust to enter theESP-desulfurization device 16 evenly. The center of ESP-desulfurizationdevice 16 is an electrostatic dedusting body 15, an automatic cleaningdevice 17 is mounted on the upper part of ESP-desulfurization device 16,and a even-flow board 18 and a wind outlet 20 is located on the top ofESP-desulfurization device 16. Via a water pump 8, the water pipe in theclear water tank of the tank 10 is connected to the water sprayingdevice 2 of the wet type dust removal-desulfurization device 3 and theautomatic cleaning device 17 of the electrostatic dustremoval-desulfurization device 16.

The process is described as follows: Through the wind inlet 1, the sootdust (black smoke) enters the wet type dust removal-desulfurizationdevice 3 first for the first-stage dust removal-desulfurizationtreatment. When the soot dust (black smoke) passes through the holes ofthe mesh screen 4 together with water, the smoke soot and black carbonof the smoke dust will be hydrophilic forcibly, thus creating anecessary condition for the second-grade electrostatic dedusting. Then,the primary purified soot dust (black smoke) enters theESP-desulfurization device 16 via the smoke duct 13 for the second-stagedust removal-desulfurization treatment. After being hydrophilic, thespecific resistance of the soot and black carbon is increased to reachthe specific resistance scope of the high electrostatic dedustingefficiency, the ESP-desulfurization device 16 can remove the black smoke(soot and black carbon) from the smoke efficiently, and will notreturned to the airflow, thus reaching the purpose of removing the smokedust (black smoke) efficiently. Furthermore, being adsorbed in theelectrostatic dedusting body 15 of the ESP-desulfurization device 16,the black smoke (soot and black carbon) can be washed away to the tank10 via the automatic cleaning device 17.

While we have shown and described various embodiments in accordance withthe present invention, it should be clear to those skilled in the artthat further embodiments may be made without departing from the scope ofthe present invention.

1. A device for removing soot dust of fuel oil combustion, comprising: awet type dust removal-desulfurization device; a water-spray device beingset on a top of the wet type dust removal-desulfurization device; a meshscreen having 18-30 layers and 18-30 meshes whose tangent angle to aflow direction of the soot dust ranges from 60° to 90°, wherein the meshscreen is set in the wet type dust removal-desulfurization device; anelectrostatic precipitator (ESP)-desulfurization device having anautomatic cleaning device and an even-flow board being set on a top ofthe ESP-desulfurization device, wherein an electrostatic dedusting bodyis a center part of the ESP-desulfurization device, theESP-desulfurization device also having a soot dust guiding board mountedon a lower part of the ESP-desulfurization device, further wherein boththe even-flow board and the soot dust guiding board evenly regulate thesoot dust flowing through the ESP-desulfurization device; and a tank,wherein the wet type dust removal-desulfurization device and theESP-desulfurization device are connected to an upper part of the tankbeing separated by a first partition board; wherein a smoke duct isformed above a water interface of the tank, the soot dust of fuel oilcombustion flows from the wet type dust removal-desulfurization deviceinto the ESP-desulfurization device for soot dust removal anddesulfurization via the smoke duct and the soot dust guiding board.
 2. Adevice for removing soot dust of fuel oil combustion according to claim1, wherein the tank is divided into a clear water tank and a waste watertank by a second partition board located at a center of the tank,further wherein a filter screen is set on a lower part of the secondpartition board to enable the waste water to be filtered before flowinginto the clear water tank.
 3. A device for removing soot dust of fueloil combustion according to claim 2, further including a manualdust-removing mouth located on one side of the tank under the watersurface, a wastewater discharge outlet set at a lower part of the tank,and an agent-filling opening located on the other side of the tank abovethe water surface.
 4. A device for removing soot dust of fuel oilcombustion according to claim 2, further including a wind inlet set inan upper part of the wet type dust removal-desulfurization device, awind outlet located on the top of the ESP-desulfurization device,wherein the even-flow board is set under the wind outlet.
 5. A devicefor removing soot dust of fuel oil combustion according to claim 2,wherein a water pipe in the clear water tank is connected to thewater-spray device of the wet type dust removal-desulfurization deviceand the automatic cleaning device of the ESP-desulfurization device viaa water pump.
 6. A method of removing soot dust of fuel oil combustionusing the device of claim 1, comprising: spraying water to the soot dustof fuel oil combustion from top to bottom as the same flow direction ofthe soot dust of fuel oil combustion by a water-spay device, the sootdust of fuel oil combustion being forcibly hydrophilic with water, thesoot dust of fuel oil combustion being surrounded and extruded by waterwhile forcing through a mesh screen having several layers and meshestogether with water, by which surface physical properties of the sootdust of fuel oil combustion are changed, including overcoming a drawbackof the hydrophobic nature and increasing a specific resistivity of thesoot and black carbon in the soot dust of fuel oil combustion; removingthe soot and black carbon, whose surface physical properties have beenchanged, by an electrostatic precipitator (ESP)-desulfurization device;and washing away the soot and black carbon collected by theESP-desulfurization device to a tank.
 7. A method of removing soot dustof fuel oil combustion according to claim 6, wherein a temperature-heatenergy of a smoke of fuel oil plays an active catalytic effect to areaction of the soot dust and black carbon, being hydrophilic withwater.
 8. A method of removing soot dust of fuel oil combustionaccording to claim 6, wherein the mesh screen has 18-30 layers and 18-30meshes.